Large amounts of highly enriched uranium metal will be entering the global marketplace as a result of the dissolution of the Soviet Union and its large nuclear arsenal. For the new republics of the former Soviet Union, the highly enriched uranium metal derived from the former Soviet Union's nuclear arsenal represents a much needed source of income. However, the prospect of nuclear weapon grade uranium becoming accessible to countries who do not presently possess nuclear weapon capability is a subject of significant concern. In response to this concern, the United States has legislated the creation of the United States Enrichment Corporation (USEC). One of the objectives of the USEC is the purchase of the highly enriched uranium metal from the republics of the former Soviet Union. The uranium purchased is to be converted into a lower grade of enriched uranium that is not suitable for use in nuclear weapons.
Several significant problems face any party seeking to purchase and transport the highly enriched uranium from the former Soviet Union. Assaying such highly enriched uranium will be difficult, since the uranium is not expected to have homogeneous isotope or elemental content. Each batch of highly enriched uranium sold will likely come from a variety of weapons, each with a different production history. Further, the uranium will most likely be offered for sale as unrecognizable pieces of metal, each possessing a different elemental and isotopic composition. In addition, given the monetary value of highly enriched uranium, there is a strong likelihood that the parties offering the uranium for sale may attempt to dilute the highly enriched uranium with lesser grade uranium in order to enhance the profits derived from these transactions.
The politically sensitive nature of this material also increases the likelihood that parties, either at the personal (individual worker) or official (government) level, will attempt to divert some of the highly enriched uranium.
At present, an efficient method for determining the overall isotope and elemental composition of large quantities of inhomogeneous chunks of uranium metal is needed. Given the large volume and the radioactive property of this material, sampling each individual piece of metal is neither practical nor suitable. Given the piece by piece inhomogeneity of the uranium metal, a large number of random samples would need to be tested in order to obtain a statistically accurate measurement of the average isotope and elemental content of the uranium. However, even with random sampling, substitutions and/or diversions can nonetheless occur in a statistically significant manner.
Transportation of highly enriched uranium is a second significant problem, since the shipment of material which is 20 wt % or more .sup.235 U is subject to restrictive NRC guidelines.